HTML oninvalid事件用法及代碼示例

當我們提交無效的元素時，將發生HTML DOM oninvalid事件。例如，輸入字段是可提交的，並且設置了必填屬性，則如果該字段為空，則該屬性無效。

用法:

在HTML中：
```
<element oninvalid="myScript">
```

在JavaScript中：

object.oninvalid = function(){myScript};

在JavaScript中，使用addEventListener()方法：
```
object.addEventListener("invalid", myScript);
```

範例1：使用HTML。

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
      HTML DOM oninvalid Event 
  </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
        <form> 
            email:
            <input type="email"
                   oninvalid=""
                   name="email" 
                   required> 
            <br> 
            <input type="submit"
                   value="Submit"> 
        </form> 
    </center> 
</body> 
  
</html>

輸出：

範例2：使用JavaScript。

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        HTML DOM oninvalid Event 
    </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
        <form> 
            Email:
            <input type="email" 
                   id="emailid"
                   name="email" 
                   required> 
            <br> 
            <input type="submit" 
                   value="Submit"> 
        </form> 
  
        <script> 
            document.getElementById( 
              "emailid").oninvalid = function() { 
                (GFGfun) 
            }; 
  
            function GFGfun() { 
                alert("Please fill out the required fields."); 
            } 
        </script> 
    </center> 
</body> 
  
</html>

輸出：

範例3：使用addEventListener()方法：

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        HTML DOM oninvalid Event 
    </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
  
        <form> 
            Email:
            <input type="email" 
                   id="emailid"
                   name="email"
                   required> 
            <br> 
            <input type="submit"
                   value="Submit"> 
        </form> 
  
        <script> 
            document.getElementById( 
                "emailid").addEventListener( 
                "invalid", GFGfun); 
  
            function GFGfun() { 
                alert( 
                    "Please fill out the required fields."); 
            } 
        </script> 
    </center> 
</body> 
  
</html>

輸出：
之前：

後：

支持的瀏覽器：下麵列出了HTML DOM oninvalid Event支持的瀏覽器：

穀歌瀏覽器
Internet Explorer 10.0
Firefox
蘋果Safari
Opera

相關用法

注：本文由純淨天空篩選整理自Vijay Sirra大神的英文原創作品 HTML | DOM oninvalid Event。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。